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author | Dean Jenkins <Dean_Jenkins@mentor.com> | 2013-02-28 14:21:54 +0000 |
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committer | Gustavo Padovan <gustavo.padovan@collabora.co.uk> | 2013-03-08 10:40:24 -0300 |
commit | c06f7d532aa6f78b2847e3b651c0da27fc3296c0 (patch) | |
tree | 902e64424ee35ba3a415ebb45b75f06b4cb161d2 /net/bluetooth/rfcomm/core.c | |
parent | fea7b02fbf73adb2e746f00ed279a782de7e74e4 (diff) | |
download | linux-c06f7d532aa6f78b2847e3b651c0da27fc3296c0.tar.gz linux-c06f7d532aa6f78b2847e3b651c0da27fc3296c0.tar.bz2 linux-c06f7d532aa6f78b2847e3b651c0da27fc3296c0.zip |
Bluetooth: Check rfcomm session and DLC exists on socket close
A race condition exists between near simultaneous asynchronous
DLC data channel disconnection requests from the host and remote device.
This causes the socket layer to request a socket shutdown at the same
time the rfcomm core is processing the disconnect request from the remote
device.
The socket layer retains a copy of a struct rfcomm_dlc d pointer.
The d pointer refers to a copy of a struct rfcomm_session.
When the socket layer thread performs a socket shutdown, the thread
may wait on a rfcomm lock in rfcomm_dlc_close(). This means that
whilst the thread waits, the rfcomm_session and/or rfcomm_dlc structures
pointed to by d maybe freed due to rfcomm core handling. Consequently,
when the rfcomm lock becomes available and the thread runs, a
malfunction could occur as a freed rfcomm_session structure and/or a
freed rfcomm_dlc structure will be erroneously accessed.
Therefore, after the rfcomm lock is acquired, check that the struct
rfcomm_session is still valid by searching the rfcomm session list.
If the session is valid then validate the d pointer by searching the
rfcomm session list of active DLCs for the rfcomm_dlc structure
pointed by d.
Signed-off-by: Dean Jenkins <Dean_Jenkins@mentor.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Diffstat (limited to 'net/bluetooth/rfcomm/core.c')
-rw-r--r-- | net/bluetooth/rfcomm/core.c | 26 |
1 files changed, 24 insertions, 2 deletions
diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c index d301fbbe2098..d9e97cf1792b 100644 --- a/net/bluetooth/rfcomm/core.c +++ b/net/bluetooth/rfcomm/core.c @@ -493,12 +493,34 @@ static int __rfcomm_dlc_close(struct rfcomm_dlc *d, int err) int rfcomm_dlc_close(struct rfcomm_dlc *d, int err) { - int r; + int r = 0; + struct rfcomm_dlc *d_list; + struct rfcomm_session *s, *s_list; + + BT_DBG("dlc %p state %ld dlci %d err %d", d, d->state, d->dlci, err); rfcomm_lock(); - r = __rfcomm_dlc_close(d, err); + s = d->session; + if (!s) + goto no_session; + + /* after waiting on the mutex check the session still exists + * then check the dlc still exists + */ + list_for_each_entry(s_list, &session_list, list) { + if (s_list == s) { + list_for_each_entry(d_list, &s->dlcs, list) { + if (d_list == d) { + r = __rfcomm_dlc_close(d, err); + break; + } + } + break; + } + } +no_session: rfcomm_unlock(); return r; } |